Process of furifying argon and preparing oxidized products



Sept.,29, 1925.

P. E. HAYNES PROCESS,V l01"' PURIFYING ARGON AND PREPARING VOXIDIZED PRODUCTS Filed May 5, l

3mm/11M:

www.

lPatented Sept. 29,' 1925.

l UNITED STATES PIERRE E. HAYNES, OF BUFFALO, NEW YORK, ASSIGNOR T THE LINDE PRODUCTS I issasm PATENT OFFICE.

- COMPANY, A CORPORATION 0F OHIO.

PRocEss or PURIFYING Anson AND PREPARING oxInIzED PRODUCTS.

Aaplication :nea May a, 1922. serial No. 558,247.

To all whom t may concern.:

Be it known that I, PIERRE E. HAYNES, a citizen of the United States, residing at Buffalo, in the county of Erie and State of 6 New York, have invented certain new and.

useful Improvements in Processes of Purifying Argon and Preparing Oxidized Products, of which the following is a specification.

This invention relates tothe production of argon, or argon-nitrogen mixtures, and to the manufacture of lead oxids. More particularly, the invention comprises the fixation of the oxygen content of mixtures of l the atmospheric gases in the form of an oxid of lead, the process being preferably so regulated as to obtain a product containing a desired percentage of minium. The term minium is used herein to designate a definite chemical compound of the composition Pb3O4, while the term red lead is reserved for commercial products having oxygen contents intermediate those of PbO. Aand PbO-, and probably comprising mixtures of minium with relatively small amounts of lower oxids.

According to the present invention, air maybe treated for the production ofargon, either directly or after suitable modification of its composition by physical or chemical means. For most industrial purposes, argon should be completely free from oxygen, carbon dioxid, and Water vapor, and should contain not more than a small percentage of nitrogen. A product of this degree of purity can be conveniently obtained by operat,

ing upon commercial compressed oxygen,

prepared by fractional distillation of liquid i air, and I shall describe my process as applied to this as the source of the gaseous mixture to beA deoxidized. -The average .composition of commercial oxygen is about 98% oxygen, 1% argon and 1% nitrogen. The argon percentage of course includes the other inert atmosphericgases, which are inseparable except b complicated physical processes. l Where argon is mentioned in the succeeding description and in the claims,

it should be understood to mean argon in admixture with the other inert gases, as I do not contemplate their removal.

The invention will be described in connection with the accompanying drawing, in which the ligure is a diagrammatic, partly sectional, illustration' bf an apparatus for carrying out the process.

Referring to the drawing, reference` nu-` vided on the container. A pipe 5 conducts` the gas mixture to a meter 6, through which it passes Ainto pipe 7 leading into a rotary tube `furnace 8. A safety sealv 9 is interposed in the line between the container and meter.

The tube 8 is enclosed in a furnace chamber 10 heated by burners 11 and having a stack 12' for escape of combustion gases. Hollow shafts 13 and 14 are fixed' upon the ends of tube 8 and are journalled in standards 15 and 16. A. pulley 17 isrigidly secured to shaft 13, and is rotated by belt 18 which is driven by motor 19.

Hollow shafts 13 and 14 receive' pipes 7 and 20, respectively. The former pipe is bent into a helical coil 21 which extends substantially the entire length of the furnace tube. -Pipe 20 is welded or otherwise secured to pipe 7 at 22, the pipe extends in a straight length 23, in alinement .with pipe 20, and is provided with nozzles 24. This arrangement of pipes 7, 21, and 23, causes the oxygen to traverse a circuitous path in which its temperature is raised to a suitable degree before it is discharged. into the furnace. Perforations 25 in that part of pipe 20 which lies Within the furnace tube permit the exit of gases which have escaped combination inthe furnace. The tube is provided with baflles 27 to assist in the agitation of the charge.

A thermometer 28 is inserted in theend of pipe 20, in contact with the eilluent gases. Such gases may be drawn off through branch pipe 29 and stored or utilized as desired.

The preferred procedure for preparing argon and red lead is as follows: The furnace tube 8 is charged with pig lead through a charging door (not shown) and the temperature ofthe interior of the tube is raised to at least 340 C. to melt the lead. The oxygen-argon gas mixture is then admitted and the tube rotated. The rate of flow of gasv is so adjusted that the oxygen is substantially completely fixed by reaction with the lead. The oxygen absorption is veryv rapid at first, but a lower, substantially constant absorption rate is soon established,`

which is maintained until the greater portion of the lead has been oxidized. The operating conditions largely determine the permissible rate, but in any case a simple test of the effluent gas will indicate Whether `oxygen is being fed in at a higher rate vthan that at which it can be absorbed. The pressure may be controlled by the regulator 4, but it is advisable to insert the safety seal 9 to permit the escape -of gas should it be supplied under excess pressure.

The temperature of the furnace is main-` trative of the improved process: A gas consisting of 98.25% oxygen, 0.80% argon, and 0.95% nitrogen is passed at a rate insuring satisfactory oxygen absorption over a charge of molten lead in a rotating furnace. The

temperature is maintained around 350 C.- The eilluent gas has an oxygen content be` low 1%. The process is continued for about.

24 hours. The oxidation of the lead at this time is substantially complete, the voxid produced corresppnding in composition to a mixture containing approximately 50% minium and 50% massicot. This is a desirable mixture for certain industrial purposes, such as the manufacture of storage battery plates, and I prefer to arrest the process at this stage.

In an application Serial No. 558,246 filed of even date herewith by J. B. Huffard and P. E. Haynes; there is described the regulation of the process of oxidizing metallic lead with oxygen so as to obtain the desired percentage of minium. Such methods may be utilized in connection with the 4preparation of argon, as well as the specific oxidation processdescribed herein.

Where argon of higher purity than that obtained as described above is desired, the effluent gas may be passed through ammoniacal copper solutions, over red hot copper,

or treated with other reagents capable of removing the last traces of oxygen. Oxygen together with part or all of the nitrogen may be eliminated .by treatment with metallic magnesium at elevated temperatures, or in other suitable ways.

I have found that the removal of oxygen is satisfactory not only when a relatively large proportion of metallic lead is present,

but also when a stage of incomplete oxidation has been reached in the process of`producing red lead. y The lower loxids of lead may therefore be used to deoxidize theoxygen-argon mixture. In some cases, it is desirable to pass the gas remaining after the treatment with the lower oxids, over lead in a less oxidized condition, or over fused metallic lead, to remove oxygen which may- My invention as distinguished from such methods, resides i'n the described process for f eliminating oxygen from Igas mixtures containing argon by causing the gas to` come into intimate contact with a bod of molten heavy metal undergoing agitation. Fresh surfaces for oxidation are constantly 'exposed and the process may therefore be conducted continuously for long periods with a large production of argon substantially free from oxygen. From the commercial point of view, it is obviously of importance to fix the oxygen in the form of a salable compound, but so far as I am aware, it has not heretofore been realized that argon could be obtained with the simultaneous production of a valuable oxidized roduct. As pointed out in my application a ove referred to, important technical advantages result from theuse of a gas rich in oxy en for the manufacture of lred lead, and as s own herein, such process is admirably adapted also for the production of argon. V

While in the preferred form of my invention the separation of argon is combined with the production of lead oxids, it willvbe understood that other readily4 oxidizable metals or alloys fusible at atemperature sufficiently low to be used in an apparatus of the kind described, or metal oxids capable of being raised to a higher stage of oxidation, are` suitable for the fixation of the oxygen. As examples, zinc, tin, or a low oxid of iron may be mentioned. Commercial compressed oxygenis not 7necessarily selected as the oxidizing gas, as other'argoncontaining gases, including argon partly freed from oxygen or nitrogen by a preliminary treatment, may be utilized in my,

process. Further modifications of the process as described may be made within the scope of the appended claims.

I claim:

1. Process of separating a reactive gas from argon, comprising passing the mixed gases' over a molten metal capable of fixing such reactive gas and continuouslyagitated 4in contact therewith. v 2. Process of removing oxygen from ad-- mixture with small amounts .of nitrogen A and argon, .comprising passing' the mixed gasesI into intimate contact with molten lead, andV collecting the eiliuent gas.

3. The invention according to' claim 2, in

which the metal is contained in Ka furnace which` is continuously rotated` during the passage of the gas'.

'tained at a' temperature above its 4. Process of purifying` argon and pre paring an oxid of lead, comprising passing 4 a gaseous mixture containing oxygen and argon, in proportions' greaterthan 1n at-' mospheric air, intocontact with lead mainmelting point, and collecting the eluentgas.

5. Process of purifying argon and prepar-I ing an oxid of lead, comprising meltinglead and agitating the same in a stream of gas containing oxygen and argon in proportions eater than in atmospheric air, and collect-` .ing the effluent gas.

and 1% nitrogen into contact wit lead maini,555,57o v i `lead heated to a temperature above 340? C passlng commercial s oxygen containing approximatelyl7 :tained at a temperature above its melting point, the rate of flow of thegases being such that substantially all the oxygen reacts with the lead. r

8. 'Process according to claim 7, in which the process is continued until substantially all ythe lead is oxidized.

9. Process of preparing leadoxids,'includ ing mnium, which comprises charging lead into a rotary furnace, melting and continuously heating the lead, rotating the furnace to agitate the lead, passing into thefurnace a gas containing oxygen in admixture with a small amount of argon, until the desired percentage of mnium is formed, and collectingthe eflluent gas containingargon substantially free from oxygen.

10. `Process of removing oxygen from an oxygen-argon gas mixture, comprising passing saidvmixture over a able of reacting with oxygen.- i

11. Process of removing oxygen 'from an oxygen-argon gas mixture, and preparing a commercially valuable oxid, comprising passing said mixture over a'lower oxid of whereby the oxygen is absorbed v`with th formation of an oxid of lead ox gen content. n testimony whereof I'aliix my signature.

PIERRE n. HAYNEs.

having a high metallic oxid i cap- A 

